Veteran director Robert Altman, late in his career and long in the tooth, turns in a masterful, playful, multi-layered period piece that compares with his finest films. Set in England during the '30s, "Gosford Park" is an upstairs/downstairs inspection of a posh weekend at a country estate lorded over by a heartless, overbearing patriarch. The fact that this rapier-like comedy of manners (with a bit of sex tossed in) eventually turns into a deliciously sordid murder mystery is just a bonus. As in "Harry Potter & the Sorcerer's Stone," the list of performers here reads like a Who's Who of the British acting community. Maggie Smith, Michael Gambon and Kristin Scott Thomas are some of the upper-crusters; Jeremy Northam is a matinee idol; Helen Mirren, Emily Watson, Richard E. Grant and Derek Jacobi are among the help; and Stephen Fry is a pompous police inspector. Two American actors, Ryan Philippe and Bob Balaban, are aboard as the nouveau-riche Yankee contingent, but they rise to the occasion.